England and Wales will have a bright day with plenty of sunny spells, and although most parts will stay dry, the odd brief, light shower cannot be ruled out.
Top temperatures of 22 Celsius (72 F).
Meanwhile, Northern Ireland and Scotland will begin dry, but rain will arrive in western parts though the morning and it will become increasingly windy.
During the afternoon, the rain will arrive in the rest of Northern Ireland and Scotland, with some heavy bursts later this evening.
It will also become increasingly windy overnight, with severe gales through the early hours of Thursday morning, and a yellow weather warning is in force.